Vortex reaction type fluid flow indicator

ABSTRACT

A fluid flow indicator having (a) a vortex reaction responsive oscillatable member disposed within a conduit, for transmitting energy non-mechanically through the conduit wall to a responder located outside the conduit to provide a response that is a measure of the fluid flow. The non-mechanical transmission through the conduit wall may be by way of electromagnetic radiation caused for example: by a moving magnetic element producing a relatively moving magnetic field; or by radioactivity. The responder responds to electromagnetic radiation in the specific form employed, field disturbance or change by a moving magnetic member, or radioactivity, as the case may be.

United States Patent Kivenson [54] VORTEX REACTION TYPE FLUID FLOWINDICATOR [72] Inventor: Gilbert Kivenson, Pasadena, Calif.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Sept. 18, 1970 [21] Appl. No.: 73,543

[52] US. Cl ..73/194 B, 340/239 R [51] Int. Cl. ..G0lf 1/00 [58] Fieldof Search ..73/194 13, 70.2, 71.2, 71.4;

335/205; ZOO/81.9 M; 340/239 [56] References Cited UNITED STATES PATENTS1,935,445 1l/1933 Heinz ..73/194 B 2,600,01 1 6/1952 MacDonald etal..200/8 1.9 M 2,600,309 6/1952 MacDonald et a1..200/81.9 M 2,813,42411/1957 Liepmann et al.....73/l94 B X 3,116,639 1/196'4 Bird ..73/194 B3,175,399 3/1965 Medlar ..73/194 B 3,273,389 9/1966 Waugh ..73/194 B[451 Aug. 15, 1972 3,419,877 12/1968 'Roth ..335/205X FOREIGN PATENTS ORAPPLICATIONS 992,852 5/ 1965 Great Britain ..335/205 PrimaryExaminer-Charles A. Ruehl Att0rney--F. H. Henson, R. G. Brodahl and C.J. Paznokas 5 7] ABSTRACT A fluid flow indicator having (a) a vortexreaction responsive oscillatable member disposed within a conduit, fortransmitting energy non-mechanically through the conduit wall to aresponder located outside the conduit to provide a response that is ameasure of the fluid flow. The non-mechanical transmission through theconduit wall may be by way of electromagnetic radiation caused forexample: by a moving magnetic element producing a relatively movingmagnetic field; or by radioactivity. The responder responds toelectromagnetic radiation in the specific form employed, fielddisturbance or change by a moving magnetic member, or radioactivity, asthe case may be.

5 Claims, 5 Drawing Figures Patented Aug. 15, 1972 UTILIZATION a o E 5 62 T Y w I M .H 6/ R R m. 0 O M 0T AT m m W D D O IN I S u c H F Q FLUIDFLOW |2 FIG.4.

CIRCUIT UTILIZATION/56 RADIOACTI \IIITY DETECTOR ww I a MN .I. N E W J.VI I T WU T G M.

RADIOACTIVE SOURCE VORTEX REACTION TYPE FLUID FLOW INDICATOR BACKGROUNDOF THE INVENTION It is often necessary for chemical and power plantoperators to have quantitative and non-quantitative indications of fluidflow in a piping system. This information might be required, forexample, to check on the proper functioning of various types ofmachinery, to 1 measure fluid quantity, or to predict the onset ofdangerous operating conditions.

One class of device used at present consists of a pivoted plate mountedin a horizontal section of pipe. The plate can be observed through sidewindows. In the noflow condition, the plate hangs vertically. When flowstarts, the plate swings out on its pivot to an angular position whichis roughly proportional to the flow of velocity. The operator judges thepresence of flow partly by the deviation of the plate from vertical andby minute motions it makes in response to velocity variations.

Another widely used flow indicator contains a rubber ball looselytrapped between two screens. The apparatus is arranged so that the flowmust pass through the screens. The ball is first pushed towards thedownstream screen; it rebounds and is again caught in the flow. Rotaryas well as translational motion is induoed in the ball. The movement isobserved through windows in the side of the apparatus.

A major difficulty with the devices described above lies in the use of awindow. The latter prevents application of the instrument to highlycorrosive liquids which would destroy the packing materials used asseals or would etch the glass itself. In nuclear power plants, flowindicators or this type would not be desirable because of lowreliability at high pressure and temperature. Opaque liquids andslurries cannot be handled by these devices since observation of themoving elemen is difficult.

It is known to transmit information from inside a conduit to the outsideby means of mechanical coupling between a movable inside member and anoutside indicator. However, this presents a problem with seals whichneed to resist fluid pressure, and need resist attack in the case ofcorrosive fluids.

It is also known to transmit such information by means of magneticcoupling between an inside magnetic member and an outside indicatingdevice. However, the devices of the prior art employing such magneticcoupling have been of limited applicability and value.

It is known in the art of vortex reaction flo'w meters to mechanicallycouple a vortex reaction element located inside a conduit to a magneticmember outside the conduit which in turn is magnetically coupled to acoil in such a manner as to change flux linkages with the coil inresponse to oscillation of the vortex reaction element, thereby toinduce voltages in the coil. This of course is subject to all thedisadvantages of transmitting mechanical coupling through the wall ofthe conduit.

While the desirability of indicating conditions in fluid lines by meansof magnetic coupling between inner and outer members has been known formany years, to the best of my knowledge, this principle has not beenapplied to vortex reaction flow meters prior to my invention. A likelyreason for this is that specific structures not suggestive for use inconnection with vortex reaction type fluid flow meters.

SUMMARY OF THE INVENTION The present invention overcomes above discussed0 disadvantages by a unique flow indicating device having a vortexresponsive oscillatable member inside a fluid conduit for transmittingenergy non-mechanically through the conduit wall to a responder thatresponds to such energy transmission and thereby provide an indicationof fluid flow. Such non-mechanical transmission through the conduit wallmay be transmission'of energy by electromagnetic radiation, for example,by radioactivity, or by a moving magnet or by X-rays, or by light. Thevortex driven transmission member may for example be a radioactivesource itself, or it may be a movable shutter interposed between aradioactive source and an external responder sensitive toelectromagnetic radiation from a radioactive source.

In another example, the vortex driven energy transmission member is amagnet, and the external responder to the electromagnetic radiation ofthe moving magnet is a magneto-responsive device magnetically coupledthrough the conduit wall to the internal vortex driven magnet to providea response indicative of fluid flow. The magneto-responsive device maybe an oscillatable magnetic element, in which case the response of thatelement may be visible. The magnetoresponsive device may be a pickupcoil, in which case the response is an electric signal generated in thecoil by the magnetic field variations produced by an oscillatinginternal magnetic member. The signal may, with or without processing beapplied to indicating apparatus or to control apparatus. Examples ofindicating apparatus are flow rate indicators and total fluid quantityindicators.

DESCRIPTION OF THE DRAWINGS 1 is a partially exploded and partially cutaway view of one embodiment of the invention;

FIG. 2 is a view, partly mechanical and partly electric block diagram,illustrating another embodiment of the invention;

FIG. 3 is a section taken along the line III-III of FIG.

FIG. 4 is a diagram illustrating use of magnetic responder as a singlepole-double throw switch in an indicating circuit; and

FIG. 5 is a sectional view illustrating the use of the vortex drivenelement as a shutterinterposed between a radioactive source and aresponder located outside the conduit and responsive to radioactivity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown a section of pipe or conduit 10 adapted for insertion in afluid line wherein the fluid flow is in the direction of the arrow 12.Thus the left end of the conduit 10 is the upstream end, while the rightend is the downstream end. Disposed within the pipe 10 is a vortexresponsive oscillatory member 14 at least a portion of which ismagnetic. The member 14 is provided with a head portion 16, a rootportion 18 anchored in a block 20, and a flexible intermediate portion22 between the head and root protions. The block 20 is fixed to theinner walls of conduit by means of struts 24. The block and struts 24are made small to minimize flow impedance. By way of example, themagnetic portion of the member 14 is the head portion 16, and by way offurther example the head 16 is a permanent magnet. The intermediateportion 22 of member 14 is shown as a flat spring which at rest lies ina plane parallel to the direction of fluid flow, whereby the head 16 mayoscillate laterally or crosswise of the fluid flow direction in aconstrained path due to the flat configuration of the spring. Thus inthe example disclosed, the intermediate portion 22 is resilient as wellas flexible.

Mounted on the exterior of the pipe 10 is a responder 26 for respondingto the movements of the oscillatable member 14. The responder 26,similarly to the member 14, includes a resiliently mounted magneticportion which is magnetically coupled to the magnetic portion of themember 14. More specifically, the responder 26 is provided with amagnetic head 28 fixed to one end of a flat spring 30 whose other end issecured in a block 32 that is attached to the exterior of the pipe 10.The orientation of responder 26 is spaced parallelism with the member 14such that the heads 16 and 28 are substantially in line with each otherand the flat dimensions of springs 22 and 26 are in substantially thesame plane parallel to the main direction of fluid flow. Preferably thereferred to plane is a vertical plane to avoid gravity sag of thesprings.

For magnetic coupling to exist between the magnetic heads 16 and 28 sothat head 28 will follow the lateral oscillations of head 16, at leastone of the heads must be a magnet, and at least that portion of theconduit wall which is between the magnetic heads should be made ofnon-magnetic material such as plastic, brass, aluminum, Type 304stainless steel, or other. Preferably, both heads 16 and 28 arepermanent magnets. Head 28 is shown smaller than head 16 for betterresponse. Spring 30 is also shown shorter than spring 22 to providemotion amplification.

Since it is necessary that a sufficient expanse of conduit wall betweenthe member 14 and responder 26 be non-magnetic in order to effectoperative magnetic coupling between member 14 and responder 26, it maybe more convenient and in some cases preferable to make the entireconduit section 10 of non-magnetic material. The responder 26 is coveredby a protective housing 36 mounted on the conduit 10 and provided with atransparent observation window 38 through which the responder 26 may beviewed. The housing 36 is shown exploded" away from the conduit. Eitherthe window or the conduit surface beneath the responder may be suitablymarked with an index or scale to indicate or measure the deflection ofthe responder. The notations may for example be in terms of flow rate.

As will presently be explained, the head 16 is vortex driven in responseto fluid flow through the pipe 10, and will oscillate at a frequencythat is a function of the flow rate or velocity of the fluid. Due to themagnetic coupling between the heads 16 and 28, the head 28 will followthe movements of head 16 to provide a visual indication of flow rate.

It is well known that the vortices are formed when a fluid streams pastan obstruction or through an orifice at a velocity lying within a rangebetween certain lower and upper values that are both dependent on thedimensions of the obstruction or orifice and the kinematic viscosity ofthe fluid. A circular cylinder, for example, placed in a stream with itslongitudinal axis at right angles to the direction of fluid flow, causesthe fluid to divide in order to permit passage around the obstruction,and when the two flows recombine, vortices are formed on the down streamside of the cylinder at regular intervals and alternately, first at oneside of the cylinder and then at the opposite side, which vorticesdetach themselves from the cylinder in two nearly parallel rows and arecarried down stream at a .relative velocity substantially proportionalto the velocity of the fluid. Such a pattern of vortices is known as thevon Karman vortex street. It is also well known that the frequency atwhich these vortices are formed is substantially proportional to therelative velocity of the fluid. The effect of ultimate shedding ofvortices is to impart a pulsating force on the cylinder alternately inopposite directions perpendicular to the fluid flow. The principleinvolved is known as von Karman vortex shedding. If the cylinder is freeto move laterally relative to the fluid flow direction, it will vibrateor oscillate in the direction of the force, that is, laterally ortransversely of the fluid flow direction. The frequency of vibration isgiven approximately by:

Where f frequency of vibration (cycles per second) u fluid velocity(feet per second) d cylinder diameter (feet) k Strouhals constant= 0.19

This relation applies in the range of Reynolds numbers between 500 and100,000. In a practical application involving the flow of water in a 2inch lD pipe and using a vibrating cylinder 0.5 inches in diameter, therange of detectable flows is 0.3 to 60 gallons per minute. Thecorresponding frequencies of oscillation of the cylinder would be 0.15and 30 cycles per second.

In the illustrated example, the head 16 is a circular cylinder with itslongitudinal axis perpendicular to the fluid flow direction, and inaccordance with the foregoing explanation is vortex driven to oscillatein the direction of the arrows 40 and 42, that is transversely of thefluid flow direction, at a frequency substantially proportional to thefluid flow rate or velocity. Because of the magnetic couplingtherebetween, the responder 26 will track or follow the oscillatingmember 14. More specifically the movement of the magnetic head 16 causesa change in the magnetic field pattern linking the heads 16 and 28 thatforces head 28 to follow head 16. Whether the magnetic field change beconsidered as a change in position, or orientation, or pattern, orstrength, or any combination of these, the result is that the responder26 responds to such change or changes of the magnetic field andtherefore responder 26 may be considered magneto-responsive. Thereference to responder 26 as being magneto-responsive is applicablewhether both heads 16 and 28 are magnets, or only one or the other is amagnet.

Although the above description of alternate vortex generation in tworows has been in connection with an obstruction in the form of acylinder of circular crosssection, similar considerations apply invarying degrees to any obstacle or cylindrical form with itslongitudinal axis at right angles to the direction of the fluid flow,even if non-circular in cross section, unless the crosssection isintentionally streamlined to avoid such vortex generation. In all casesthe result of the alternate vortex generation in two rows is to generatealternating forces on the obstruction which under suitable conditionswill set it in oscillation or vibration in a plane at right angles tothe fluid flow direction.

Alternatively, the magneto-responsive responder may be an electricalcircuit component for causing electrical effects occurring at thefrequency of or. a frequency proportional to that of the oscillatorymember 14, for example a pickup coil or a magnetic switch such as a reedswitch.

The embodiment of the invention shown in FIGS. 2 and 3, employs amagneto-responsive responder in the form of an electro-magnetic pickup50. Except for the different responder, other parts are the same as inFIG. 1. Thus, the apparatus in FIG. 2 also includes a conduit section10, a vortex driven oscillatable member 14 with a magnetic head 16attached to one end of the spring 22, whose other end is fixed in ablock 20 that is secured to the inside of the conduit by means of struts24.

The pickup 50 is diagrammatic and intended to be symbolic of any type ofpickup that will generate electrical signals in response to magneticfield changes due to movement of the magnetic head 16. In the specificexample shown, the pickup 50 includes a winding 52 on a magnetic U-shapecore 54 so orientated that variation of the air gaps between head 16 andthe legs of the core 54 due to movement of head 16 will produce varyingflux linkages with the coil 52 thus inducing a voltage in the coil whosefrequency is proportional to the fluid flow rate.

In order to provide operative magnetic coupling between head 16 and themagneto-responsive responder 50, at least one of the magnetic heads 16and the magnetic core 54 should be a magnet. By way of example, the head16 is shown as a permanent magnet while the core 54 is made ofunmagnetized magnetic material such as soft steel or iron.

The electrical output from the pickup 50 is supplied to a utilizationcircuit 56, which may for example.include any one or more of thefollowing items: A flow rate indicator 58; a total quantity of flowindicator 60;

and control apparatus 62 for controlling apparatus in the fluid system,for example flow control valves.

The flow rate indicator 58, may for example include an amplifier and anelectric frequency meter calibrated in terms of flow rate. Suitablefrequency meters for measuring the frequency of the voltage generated bypickup 50 are well known and need no further description. Likewise thetotal number of pulses or cycles of the output voltage from the pickup50, starting from a given time, may be counted by any known means whichmay be calibrated to indicate quantity of fluid flow in the elapsedtime. For example, the total flow quantity indicator may include arectifier to rectify the output from pickup 50, and pulse shapers andcounters for suitably shaping the rectified output and counting theresulting pulses to provide an indication of total quantity of fluidflow. The output from pickup 50 maybe applied to known circuits forconverting the output to a DC voltage proportional to the frequency ofthe pickup coil output, and therefore to the fluid flow rate. Suchvoltage may be applied to a suitably calibrated DC meter to indicateflow rate or velocity. Such voltage may also be integrated by suitableknown means to provide a measure of the total flow, since the totalquantity of electricity flowing in a given time is proportional to thetotal flow of fluid in the same time. The output from pickup 50 may besupplied to the control system 62 as feedback to be compared to areference for generation of an error signal in a servo system.

It should be understood that the pickup winding 52 will operate withoutthe magnetic core54, in which case, the magnetic member 16 must be amagnet.

In a variant of FIG. 3, the core 54 may be enlarged so that the poleends straddle the pipe 10 and are diametrically across from each otherand in line with the longitudinal axis of the head 16.

In another embodiment, the responder 26 of FIG. 1 may be the vibrator ofa make and break switch in series between a battery and a circuit, whicheither counts the pulses formed by the vibrating switch or measurestheir frequency, or both, depending .on the circuits employed. Countingcircuits and frequency measuring circuits are well known and need noexplanation. Along the same lines the magneto-responsive responder maybe a strategically placed magnetic reed switch mounted on the outside ofconduit 10 and within the field of influence of the magnet 16.Preferably, in the vibrating switch arrangements, the magnetic head 16is a magnet.

An example wherein the responder 26 operates as a vibrating switch isshown in FIG. 4. In this arrangement the spring 30 is then employed asthe blade of a singlepole double-throw switch with contacts and 72.Contact 70 is connected through an ammeter 74 to a junction 76 which isconnected through a battery 78 to the other contact 72. Junction 76 isalso connected to one side of a capacitor 80, whose other side isconnected to the vibrating switch blade 30. The circuit components aresuitably selected so that the capacitor will become substantially fullychanged and discharged. evenat the highest frequency of the blade 30.The average magnitude of the current flowing through ammeter 74 issubstantially directly proportional to the quantity of electricitydischarged therethrough from the capacitor per unit of time,.and issubstantially proportional to the frequency of the vibration of armature17. The ammeter may be calibrated in fluid velocity.

In FIG. 5, the vortex driven head 16 is provided with a through slit 84and operates as a shutter between a radioactive source 86 and aresponder 88 that is responsive to radioactivity. The source 86 and thedetector 88 may be provided with slits 90 and 92 that together with slit84 are aligned when the head is in the center or neutral position. Thesource 88 may for example produce gamma rays, while the detector 88responding to the gamma rays provides an electric signal having analternating component (due to vibration of shutter) to a utilizationcircuit 56 for doing any one or more of the following: indicating totalquantity of flow rate; and controlling some variable in the system. Theresponder 88 may include an ionization chamber, or a photo responsivearrangement employing a scintillator-photo multiplier combination.Instead ofa radioactive source, a source of X-rays could be employed.

As an alternative, instead of radioactivity or a moving magnet, otherforms of electromagnetic radiation may be employed, for example lightusing the shutter arrangement of FIG. '5, but with a light responsiveresponder.

It should be understood that in all embodiments of the invention theconduit wall, or atleast the area of the wall in the path of theinvolved energy transmission, must be made of material that issufficiently permeable to the specific energy transmission form employedto effect the desired transmission.

In the case of the relatively moving magnet, the conduit wall should besufficiently magnetically permeable to effect the desired transmission.In the case of radioactive energy, the wall should be permeable to suchenergy transmission. Note that in the radioactive case, the vortexdriven head 16 is desireably made of non-pervious material so that onlythe slit will pass the electromagnetic radiation from the radioactivesource.

Although shown as a circular cylinder, head 16 may be any cylindrical orgeometric shape which will be vortex driven to provide the desiredmovement of the head 16 and consequent response by the magnetoresponsiveresponders disclosed herein or their equivalents.

The invention disclosed herein provides improvements in fluid flowindicators by unique utilization of vortex driven elements magneticallycoupled to outside responders without mechanical intervention throughthe conduit walls.

It should be understood that the herein described arrangements aresimply illustrative of the principles of the invention, and otherembodiments and applications are within the spirit and scope of theinvention.

I claim as my invention:

1. Apparatus responsive to fluid flow comprising:

A. wall means defining a fluid conduit,

B. vortex-responsive oscillatory means disposed within said conduit inthe path of fluid flow and adapted to oscillate transversely of thedirection of fluid flow in response to vortex action produced by fluidflow obstruction, the oscillation of said oscillatory means being at afrequency which is a function of the velocity of fluid flow, saidoscillatory means comprising a first magnetic head portion fortransmitting magnetic field oscillations through the conduit wall, aroot portion, and an intermediate portion connecting the head portion tothe root portion, said root portion being anchored within said conduit,and said intermediate portion being flexible whereby said head portionin response to vortex reaction will oscillate laterally relative to themain direction of fluid flow; and

C. response means disposed externally of said conduit and responsive tosaid magnetic field oscillations for providing a response which variesas a function of a measure of the oscillations of said first magnetichead portion, said response means comprising a second magnetic headportion magnetically coupled to the first magnetic head portion, a fixedsecond root portion and a flexible intermediate portion connecting thesecond magnetic head and root portions, at least one of said headportions comprising a magnet, said oscillatory means and said responsemeans being disposed in laterally spaced parallel relation, wherebyoscillation of the first head portion induces oscillation of the secondhead portion due to said magnetic coupling.

2. The combination as in claim 1 wherein the first intermediate portionis a flat spring whose plane is parallel to the main direction of thefluid flow.

3. The combination as in claim 1 wherein said head portion generatesvortices and is upstream from said root portion.

4. The combination as in claim 1 wherein said magnet is a permanentmagnet.

5. The combination as in claim 4 wherein said head portion generatesvortices and is upstream from said root portion.

1. Apparatus responsive to fluid flow comprising: A. wall means defininga fluid conduit, B. vortex-responsive oscillatory means disposed withinsaid conduit in the path of fluid flow and adapted to oscillatetransversely of the direction of fluid flow in response to vortex actionproduced by fluid flow obstruction, the oscillation of said oscillatorymeans being at a frequency which is a function of the velocity of fluidflow, said oscillatory means comprising a first magnetic head portionfor transmitting magnetic field oscillations through the conduit wall, aroot portion, and an intermediate portion connecting the head portion tothe root portion, said root portion being anchoreD within said conduit,and said intermediate portion being flexible whereby said head portionin response to vortex reaction will oscillate laterally relative to themain direction of fluid flow; and C. response means disposed externallyof said conduit and responsive to said magnetic field oscillations forproviding a response which varies as a function of a measure of theoscillations of said first magnetic head portion, said response meanscomprising a second magnetic head portion magnetically coupled to thefirst magnetic head portion, a fixed second root portion and a flexibleintermediate portion connecting the second magnetic head and rootportions, at least one of said head portions comprising a magnet, saidoscillatory means and said response means being disposed in laterallyspaced parallel relation, whereby oscillation of the first head portioninduces oscillation of the second head portion due to said magneticcoupling.
 2. The combination as in claim 1 wherein the firstintermediate portion is a flat spring whose plane is parallel to themain direction of the fluid flow.
 3. The combination as in claim 1wherein said head portion generates vortices and is upstream from saidroot portion.
 4. The combination as in claim 1 wherein said magnet is apermanent magnet.
 5. The combination as in claim 4 wherein said headportion generates vortices and is upstream from said root portion.